Glutathione (GSH;gamma-Glu-Cys-Gly) is the predominant thiol in nearly all eucaryotes and in some procaryotes and is known to play a key role in protecting cells against oxygen toxicity. It is interesting, therefore, that many aerobic procaryotes, including the mycobacteria, do not make (GSH. We have shown that the mycobacteria do produce large amounts of another cysteine-containing thiol, designated actinothione, which may play a role analogous to GSH. Actinothione contains N-acetylcysteine linked to glucosamine and another sugar. Its novel structure, limited occurrence and abundant production by mycobacteria make its sensitive detection a potentially useful approach to the rapid and economical diagnosis of tuberculosis. The goal of this research is to elaborate how measurement of actinothione in biological fluids can assist in the detection of Mycobacterium tuberculosis. The specific aims of this research are: (l) to complete the elucidation of the chemical structure of actinothione; (2) to thoroughly document which bacteria produce actinothione and which do not; (3) to develop a rapid, sensitive, and simple assay for actinothione that can be performed in most clinical laboratories; (4) to determine if and how detection of actinothione can be used to assist in the diagnosis of tuberculosis; (5) to develop efficient methods for production of actinothione in quantity for use in these studies. The results of this research will also provide key information needed to assess whether antibiotics directed at blocking the synthesis of actinothione can be used to control mycobacterial growth. Successful accomplishment of the research goal could make diagnosis of tuberculosis a more rapid and reliable process.